JL Computer Consultancy

Dumping an Oracle 8 database block

January 1999

From time to time it is useful to be able to dump an Oracle block to find
out what is stored in it. In fact, until relatively recently this was the only
way to find out where the high water mark was in a data segment.

With the arrival of the dbms_space
package in Oracle 7.3.x, block dumping took a bit of a back seat; however we
are now at Oracle 8.0 and some of the new segment types such as LOBINDEX and
LOBSEGMENT are not catered for. This script is an example of how to dump a
block in Oracle 8 and is followed by the header dump from a LOBSEGMENT

In the trace file generated by this script, the most interesting, or useful,
item is the line 11 lines down starting with the word: highwater
- which tells us that the high water mark is in extent 17 (counting from 0) at
block 5. The dump also tells you explicitly (unlike the old Oracle 7 dumps)
that we currently have 93 blocks below the highwater
mark.